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Apr
15
comment Non-iterative cryptographic hash functions
It has, thanks for your help.
Apr
14
comment Non-iterative cryptographic hash functions
I agree that non-iterative is a bad word to use for this property. What do you think about non-streaming compression? I really like where you are going with this however I'm concerned about the following situation: Let $G(x) = md5(x)||x$ and $H(x)=md5(x)$, wouldn't this allow me to define $md5(x)$ as "non-iterative/non-compressing"?
Apr
13
comment Non-iterative cryptographic hash functions
@ChrisPeikert SPRPs exist for any length, thus for each $|m|$ we choose a SPRP with the correct domain size.
Apr
10
comment Non-iterative cryptographic hash functions
@otus Consider two messages $m$ and $m'$ where $f(m_2||m_3||m_4||m_4||m_3||m_2) = f(m'_2||m'_3||m'_4||m'_4||m'_3||m'_2)$ and $m_1 = m'_1$. You don't actually need to know what $m_1$ is to know you have a collision. Part of the reason I asked this question was that I was looking for a better formal definition of non-iterative because I am not satisfied by the definition I currently have.
Apr
10
comment Non-iterative cryptographic hash functions
@otus yesterday If $h$ is an iterative hash and $|m|$ is significantly longer than the message block size then you can compress most of the messaged into $f(m||r(m)\mid_b)$ and compress the remainder in a second call to $f$. One test if something is an iterative hash is: 'can I cause a collision prior to reading the entire message?'
Apr
9
comment Non-iterative cryptographic hash functions
I did some of the differential resistance work on MD6 so I'm a big fan of the design. Its a nice property of a non-iterative hash functions that you can tree hash them into an iterative design if you want to.
Apr
8
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Apr
5
reviewed Approve Non-iterative cryptographic hash functions
Apr
3
revised Non-iterative cryptographic hash functions
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Apr
3
comment Non-iterative cryptographic hash functions
@pg1989 Sponge-based hash functions like Keccak are considered iterative since the potential message space is much larger than the intermediate state (the sponge). One could imagine a construction in which the intermediate state grew in space to ensure no message entropy was lost, but it wouldn't be a sponge construction.
Apr
3
comment Non-iterative cryptographic hash functions
@pg1989 Added a more precise definition.
Apr
3
revised Non-iterative cryptographic hash functions
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Apr
3
revised Non-iterative cryptographic hash functions
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Apr
3
asked Non-iterative cryptographic hash functions
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